"We will work diligently to make sure that justice is not delayed," Peduto said, noting the officer has been suspended from regular duties and assigned to the warrant office for 30 days while the investigation continues.

Asked whether he thought the video shows excessive force, Peduto said he couldn't reach any conclusions about what happened until more evidence surfaces.

"We’re going to be asking for additional video. There should be an opportunity for us to see the entire incident, not just that one clip, to find out what happened," Peduto said. "There are professional standards on the escalation of force and we want to make sure what happened falls within the standards and not rush to judgement."

The incident began after a confrontation between Lawther, of Harmony, and anti-gay protesters who had gathered to protest the Delta Foundation's annual LGBT pride festival, Peduto said.

According to a criminal complaint, Chatterji saw Lawther hitting Eric Moure near 6th St. and Liberty Ave Sunday afternoon. As he tried to break them up, Lawther "began to push and strike me in the chest with her hands and groin area with her legs," Chatterji wrote in the complaint.

"In a rapidly evolving and tenuous situation I grabbed Lawther by the head and swung her out of the crowd," Chatterji wrote, adding that Lawther continued to strike him — and that he was hit by others in the crowd.

"To diffuse the sutation quickly before I was attacked by the crowd once more," Chatterji wrote, "I punched Lawther in the left abdomen several times to distract her enough so I could handcuff her."

Lawther then apologized to Chatterji, saying "I did not see you were a cop," according to the complaint.

Chatterji wrote that Lawther had been warned earlier not to be "so physically offensive" toward (reportedly anti-gay demonstrators) standing on the corner.

Lawther is charged with aggravated assault, which is a first-degree felony. She's also charged with simple assault, resisting arrest and disorderly conduct, all misdemeanors.

Court records show she was released from the Allegheny County Jail today after posting $5,000 bond.

The Delta Foundation responded to the announcement of an investigation: "We are pleased that Mayor Bill Peduto has issued a full investigation into the matter that occurred between the City of Pittsburgh Police officer and Ariel Lawther," according to a press release.

The organization has contacted U.S. Attorney David Hickton's office "to also inform them of the incident and launch a potential hate crime investigation."